Ratcheting mechanism for surgical stapling device

ABSTRACT

A surgical stapling device comprising a housing, an elongated portion, an end effector, and a movable handle disposed in mechanical cooperation with the housing and movable between a first open position and a second approximated position for affecting a function of the end effector. A ratchet mechanism is disposed in mechanical cooperation with the movable handle and is configured to substantially prevent the movable handle from moving towards its first open position until the movable handle reaches a predetermined position.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of U.S. patent application Ser. No.12/397,469 filed Mar. 4, 2009, now U.S. Pat. No. 8,733,611, which claimsbenefit of U.S. Provisional Application No. 61/044,611 filed Apr. 14,2008, which claims benefit of U.S. Provisional Application No.61/035,756 filed Mar. 12, 2008, and the disclosures of each of theabove-identified applications are hereby incorporated by reference intheir entirety.

BACKGROUND

1. Technical Field

The present disclosure relates generally to a surgical stapling devicefor applying surgical staples to body tissue. More particularly, thepresent disclosure relates to a surgical stapling device suitable forperforming circular anastomosis and/or treatment to internal walls ofhollow tissue organs.

2. Background of Related Art

Anastomosis is the surgical joining of separate hollow organ sections.Typically, an anastomosis procedure follows surgery in which a diseasedor defective section of hollow tissue is removed and the remaining endsections are to be joined. Depending on the desired anastomosisprocedure, the end sections may be joined by either circular, end-to-endor side-to-side organ reconstruction methods.

In a circular anastomosis procedure, the two ends of the organ sectionsare joined by means of a stapling instrument which drives a circulararray of staples through the end section of each organ section andsimultaneously cores any tissue interior of the driven circular array ofstaples to free the tubular passage. Examples of instruments forperforming circular anastomosis of hollow organs are described in U.S.Pat. Nos. 6,053,390, 5,588,579, 5,119,983, 5,005,749, 4,646,745,4,576,167, and 4,473,077, each of which is incorporated herein in itsentirety by reference. Typically, these instruments include an elongatedshaft having a handle portion at a proximal end to actuate theinstrument and a staple holding component disposed at a distal end. Ananvil assembly including an anvil rod with attached anvil head ismounted to the distal end of the instrument adjacent the staple holdingcomponent. Opposed end portions of tissue of the hollow organ(s) to bestapled are clamped between the anvil head and the staple holdingcomponent. The clamped tissue is stapled by driving one or more staplesfrom the staple holding component so that the ends of the staples passthrough the tissue and are deformed by the anvil head. An annular knifeis concurrently advanced to core tissue with the hollow organ to free atubular passage within the organ.

Besides anastomosis of hollow organs, surgical stapling devices forperforming circular anastomosis have been used to treat internalhemorrhoids in the rectum. Hemorrhoids are masses of tissue in the anuscontaining enlarged blood vessels. Internal hemorrhoids are inside theanal canal; external hemorrhoids lie outside the anal canal. Inhemorrhoidectomy, the hemorrhoids are removed. Stapled hemorrhoidopexyis a surgical procedure in which the stapling device is used to removetissue just above the hemorrhoids in order to pull the hemorrhoids backup inside the rectum and reduce the symptoms. The staples interrupt theblood flow of the superior hemorrhoidal arterial branches, cutting offthe blood supply, thus causing the hemorrhoids to shrink.

During the use of a circular stapling device for hemorrhoid treatment,the anvil head and the staple holding component of the device areinserted through and into the rectum with the anvil head and thestapling holding component in an open or unapproximated position.Thereafter, a purse string suture is used to pull the internalhemorrhoidal tissue and/or mucosal tissue toward the anvil rod. Next,the anvil head and the staple holding component are approximated toclamp the hemorrhoidal tissue and/or mucosal tissue between the anvilhead and the staple holding component. The stapling device is fired toremove the hemorrhoidal tissue and/or mucosal tissue and staple the cut.

Typically, such surgical stapling devices include a movable handle ortrigger which is movable through a firing stroke to simultaneouslyaffect formation of a circular array of staples and coring or cutting oftissue. When the movable handle is moved through only a portion of thefiring stroke during firing of the stapling device, the circular arrayof staples may not be adequately formed, nor may the tissue beadequately cut. In current instruments, when the movable handle isreleased after firing of the stapling device, the movable handle isreturned by a biasing member to its pre-fired position. This occurswhether or not the handle has been moved through a complete firingstroke or only a portion of the firing stroke. Thus, where a surgeoninadvertently fails to move the handle or trigger to complete the firingstroke and acceptable staple formation and cutting are not affected, thehandle will still return to its pre-fired position.

Accordingly, it would be desirable for a surgical stapling device toinclude a mechanism for substantially preventing the movable handle fromprematurely returning to its pre-fired position until the movable handlehas been moved substantially through the full firing stroke.

SUMMARY

The present disclosure provides a surgical stapling device comprising ahousing, an elongated portion extending distally from the housing, andan end effector, at least a portion of which is disposed in mechanicalcooperation with a distal portion of the elongated portion. A movablehandle is disposed in mechanical cooperation with the housing and ismovable between a first open position and a second approximated positionfor affecting a function of the end effector. A ratchet mechanism isdisposed in mechanical cooperation with the movable handle, and isconfigured to substantially prevent the movable handle from movingtowards its first open position until the movable handle reaches apredetermined position.

The ratchet mechanism includes a rack having rack teeth and a camsurface and disposed in mechanical cooperation with the housing, and apawl having pawl teeth and disposed in mechanical cooperation with themovable handle. The rack teeth and the pawl teeth are configured forengagement with each other. A spring is disposed in mechanicalcooperation with the movable handle and is configured to bias at leastone of the pawl and the rack towards the other such that the pawl teethand the rack teeth are in engagement with one another. Preferably, thecam surface is configured to disengage the pawl teeth and the rack teethupon the cam surface contacting the pawl for facilitating movement ofthe movable handle towards its first open position.

In a preferred embodiment, the end effector is configured for ejectionof staples therefrom upon movement of the movable handle from its firstopen position towards its second approximated position, and the ratchetmechanism is configured to substantially prevent the movable handle frommoving towards its first open position until at least one staple hasbeen ejected from the end effector.

The surgical stapling device in a preferred embodiment includes a knifeconfigured for distal translation upon movement of the movable handlefrom its first open position towards its second approximated position,and the ratchet mechanism in this embodiment is configured tosubstantially prevent the movable handle from moving towards its firstopen position until the knife has been distally translated. Preferably,the cam surface of the rack moves the pawl away from the rack after theknife has been distally translated.

The device may further include an override disposed in mechanicalcooperation with the pawl configured to allow a user to disengage thepawl teeth from the rack teeth before the movable handle reaches thepredetermined position, to allow the movable handle to be moved towardsits first open position.

The surgical stapling device may include a clip disposed in mechanicalcooperation with the ratchet mechanism and configured to releasablymaintain the pawl teeth and the rack teeth in a disengaged position.

In a preferred embodiment, the end effector includes an anvil assemblyhaving an anvil head and an anvil center rod and a shell assemblysupporting a plurality of staples, wherein the anvil assembly is movablein relation to the shell assembly between spaced and approximatedpositions.

The present disclosure also provides a surgical stapling devicecomprising a housing, an elongated portion extending distally from thehousing, and an end effector disposed adjacent a distal portion of theelongated portion and including an anvil assembly and a shell assembly.The anvil assembly includes an anvil head and an anvil center rod havinga proximal end and a distal end. The anvil head is supported on thedistal end of the anvil center rod. The shell assembly supports aplurality of staples and the anvil assembly is movable in relation tothe shell assembly between spaced and approximated positions. A movablehandle is disposed in mechanical cooperation with the housing and ismovable between a first open position and a second approximated positionfor affecting a function of the end effector. A ratchet mechanism isdisposed in mechanical cooperation with the movable handle and isconfigured to substantially prevent the movable handle from movingtowards its first open position until the movable handle reaches apredetermined position.

In one embodiment the device includes an approximation mechanismincluding an anvil retainer for supporting the anvil assembly, the anvilretainer including an annular shoulder configured to engage the anvilcenter rod to fasten the anvil center rod to the anvil retainer.

The present disclosure also provides a ratchet mechanism for use with asurgical stapling device, the ratchet mechanism comprising a rack havingrack teeth and a cam surface and a pawl having pawl teeth, wherein therack teeth and the pawl teeth are configured for engagement with eachother. A spring is disposed in mechanical cooperation with one of thepawl and the rack. The spring is positioned to bias at least one of thepawl and the rack towards the other to engage the rack teeth and thepawl teeth. The cam surface is configured to disengage the pawl teethand the rack teeth upon the cam surface contacting the pawl. The ratchetmechanism is configured to substantially prevent a movable handle of thesurgical stapling device from moving towards a first open position untilthe movable handle reaches a predetermined position.

The device may further include an override disposed in mechanicalcooperation with the pawl, the override configured to allow a user todisengage the pawl teeth from the rack teeth before the movable handlereaches the predetermined position to allow the movable handle to bemoved towards its first open position.

DESCRIPTION OF THE DRAWINGS

Various embodiments of the presently disclosed surgical stapling deviceare disclosed herein with reference to the drawings, wherein:

FIG. 1 is a top side perspective view from the proximal end of thepresently disclosed surgical stapling device in the unapproximatedposition;

FIG. 2 is a top side perspective view from the distal end of thesurgical stapling device shown in FIG. 1;

FIG. 3 is a side perspective exploded view of the handle assembly of thesurgical stapling device shown in FIG. 1;

FIG. 3A is a top perspective view of the indicator of the handleassembly shown in FIG. 3;

FIG. 4 is a side perspective view from the top of the handle assembly ofthe surgical stapling device shown in FIG. 1 with a handle sectionremoved;

FIG. 5 is a side perspective view from the bottom of the handle assemblyof the surgical stapling device shown in FIG. 4;

FIG. 6 is a side perspective exploded view of the central body portionand distal head portion of the surgical stapling device shown in FIG. 1;

FIG. 7 is an enlarged side perspective of the anvil retainer and bandportions of the central body portion shown in FIG. 6;

FIG. 8 is a side perspective view of the screw and screw stop of theapproximation mechanism of the handle assembly shown in FIG. 5;

FIG. 9 is an enlarged view of the indicated area of detail shown in FIG.3;

FIG. 9A is a side perspective view from the top of the abutment memberof the handle assembly shown in FIG. 3;

FIG. 10 is a side perspective exploded view from the proximal end of theanvil assembly of the surgical stapling device shown in FIG. 1;

FIG. 11 is a side perspective view of the retaining clip of the anvilassembly shown in FIG. 10;

FIG. 12 is a side perspective view of the distal end of the center rodof the anvil assembly shown in FIG. 10 with a removable trocar fastenedthereto;

FIG. 13 is a side perspective view of the center rod and removabletrocar shown in FIG. 11 separated one from the other;

FIG. 14 is a side perspective view from the proximal end of the anvilassembly shown in FIG. 10 with the removable trocar attached thereto;

FIG. 15 is a side, perspective view from the distal end of the anvilassembly shown in FIG. 14;

FIG. 16 is a side cross-sectional view taken through the retaining clipof the anvil assembly and removable trocar of the anvil assembly shownin FIG. 15;

FIG. 17 is an enlarged view of the indicated area of detail shown inFIG. 16;

FIG. 18 is a side cross-sectional view taken through the pivot member ofthe anvil head assembly of the anvil assembly shown in FIG. 15;

FIG. 19 is a side perspective view from the proximal end of the anvilassembly shown in FIG. 18 with the removable trocar removed;

FIG. 20 is a perspective, partial cutaway view from the distal end ofthe anvil assembly shown in FIG. 19, with the anvil head removed;

FIG. 21 is a side cross-sectional partial cutaway view of the distalportion of the anvil assembly shown in FIG. 19, with the anvil head inphantom;

FIG. 22 is a side perspective view from the bottom of the screw stop ofthe handle assembly shown in FIG. 3;

FIG. 23 is a bottom perspective view from the proximal end of the screwstop shown in FIG. 22;

FIG. 24 is a top perspective view of the cam adjustment member of thehandle assembly shown in FIG. 3;

FIG. 25 is a side view of the screw and screw stop of the handleassembly shown in FIG. 3 with the set screw and the cam adjustmentmember removed;

FIG. 26 is a side view of the screw and screw stop shown in FIG. 25 withthe set screw and cam adjustment member attached thereto;

FIG. 27 is a side view of the screw and screw stop shown in FIG. 26 withthe cam adjustment screw adjusted to increase the tissue gap;

FIG. 28 is a side view of the screw and screw stop shown in FIG. 26 withthe cam adjustment screw adjusted to decrease the tissue gap;

FIG. 29 is a top perspective view from the proximal end of the slidemember of the indicator mechanism of the handle assembly shown in FIG.3;

FIG. 30 is a bottom perspective view of the lockout member of the firelockout mechanism of the handle assembly shown in FIG. 3;

FIG. 31 is a side cross-sectional view of the surgical stapling deviceshown in FIG. 1 with the anvil assembly removed;

FIG. 32 is a side enlarged view of the handle assembly of the surgicalstapling device shown in FIG. 31 with the handle sections removed;

FIG. 33 is an enlarged view of the indicated area of detail shown inFIG. 31;

FIG. 34 is an enlarged view of the indicated area of detail shown inFIG. 31;

FIG. 35 is a perspective view from the front of the distal end of thesurgical stapling device shown in FIG. 31 with the anvil assemblyremoved;

FIG. 36 is a perspective view from the front of the distal end of thesurgical stapling device shown in FIG. 35 with an anvil assemblyattached thereto;

FIG. 37 is a side cross-sectional view of the distal end of the surgicalstapling device shown in FIG. 36;

FIG. 38 is a side cross-sectional view of the surgical stapling deviceshown in FIG. 31 with the anvil assembly attached thereto;

FIG. 39 is a cross-sectional view taken along section lines 39-39 ofFIG. 38;

FIG. 40 is a cross-sectional view taken along section lines 40-40 ofFIG. 38;

FIG. 41 is a cross-sectional view taken along section lines 41-41 ofFIG. 38;

FIG. 42 is a cross-sectional view taken along section lines 42-42 ofFIG. 38;

FIG. 43 is a cross-sectional view taken along section lines 43-43 ofFIG. 38;

FIG. 44 is a cross-sectional view taken along section lines 44-44 ofFIG. 38;

FIG. 45 is a side perspective view of the surgical stapling device shownin FIG. 38 with the anvil assembly in an approximated position;

FIG. 46 is a side cross-sectional view of the distal end of the surgicalstapling device shown in FIG. 45;

FIG. 47 is a side enlarged view of the handle assembly of the surgicalstapling device shown in FIG. 45 with a handle section removed;

FIG. 48 is a side cross-sectional view of the handle assembly of thesurgical stapling device shown in FIG. 45;

FIG. 49 is a top horizontal cross-sectional view of a portion of thehandle assembly of the surgical stapling device shown in FIG. 45;

FIG. 50 is a side view of a portion of the handle assembly of thesurgical stapler shown in FIG. 45 with the handle sections removed;

FIG. 51 is a side cross-sectional view of a portion of the handleassembly of the surgical stapling device shown in FIG. 45 after thefiring trigger has been actuated;

FIG. 52 is a side cross-sectional view of the distal end of the surgicalstapling device shown in FIG. 45 after the firing trigger has beenactuated;

FIG. 53 is a side view of the handle assembly shown in FIG. 51 with thehandle sections removed;

FIG. 54 is an enlarged view of the firing link extension engaging theabutment member of the tactile indicator mechanism of the handleassembly shown in FIG. 53;

FIG. 55 is a side cross-sectional view of the distal portion of theanvil assembly of the surgical stapling device shown in FIG. 52;

FIG. 56 is a side cross-sectional view of the distal portion of theanvil assembly shown in FIG. 55 with a portion of the anvil headassembly in phantom;

FIG. 57 is a side view of the surgical stapling device shown in FIG. 45after the anvil assembly and cartridge assembly have been unapproximateda distance sufficient to permit the anvil head assembly to pivot on theanvil center rod;

FIG. 58 is an enlarged view of the abutment member of the tactileindicator mechanism of the handle assembly shown in FIG. 53 (duringunapproximation of the anvil and cartridge assemblies) with the wing ofthe screw stop, shown in phantom, in engagement with the abutmentmember;

FIG. 59 is a side cross-sectional view of the anvil assembly shown inFIG. 56 as the anvil head assembly begins to tilt;

FIG. 60 is a side cross-sectional view of the anvil assembly shown inFIG. 59 with the anvil assembly tilted;

FIG. 61 is a side view of the surgical stapling device shown in FIG. 45with the anvil head assembly unapproximated and tilted.

FIG. 62 is a side cross-sectional view of another embodiment of thepresently disclosed surgical stapling device with the anvil assemblyremoved from the anvil retainer;

FIG. 63 is a side cross-sectional view of the surgical stapling deviceshown in FIG. 62 with the anvil assembly attached to the anvil retainerin the open position;

FIG. 64 is a side cross-sectional view of the anvil assembly of thesurgical stapling device shown in FIG. 63;

FIG. 65 is a side cross-sectional view of the surgical stapling deviceshown in FIG. 63 with the anvil assembly in the approximated position;

FIG. 66 is a side perspective view from the proximal end of the retainerextension of the surgical stapling device shown in FIG. 65;

FIG. 67 is a side view of the retainer extension shown in FIG. 66;

FIG. 68 is a top cross-sectional view of the retainer extension shown inFIG. 67;

FIG. 69 is a top view of the anvil retainer of the surgical staplingdevice shown in FIG. 65;

FIG. 70 is a side view of the anvil retainer shown in FIG. 69;

FIG. 71 is an enlarged view of the indicated area of detail shown inFIG. 70;

FIG. 72 is a side view of the outer housing portion of the shellassembly of the surgical stapling device shown in FIG. 65;

FIG. 73 is a top view of the outer housing portion of the shell assemblyshown in FIG. 72;

FIG. 74 is a cross-sectional view taken along section lines 74-74 ofFIG. 72;

FIG. 75 is a cross-sectional view taken along section lines 75-75 ofFIG. 73;

FIG. 76 is a side view of the inner guide portion of the shell assemblyof the surgical stapling device shown in FIG. 65;

FIG. 77 is a top view of the inner guide portion of the shell assemblyshown in FIG. 76;

FIG. 78 is a side cross-sectional view of the inner guide portion of theshell assembly shown in FIG. 77;

FIG. 79 is a top cross-sectional view of the inner guide portion of theshell assembly shown in FIG. 77;

FIG. 80 is a side view of the pusher of the surgical stapling deviceshown in FIG. 65;

FIG. 81 is a top view of the pusher shown in FIG. 80;

FIG. 82 is a side cross-sectional view of the pusher shown in FIG. 81;

FIG. 83 is a top cross-sectional view of the pusher shown in FIG. 82;

FIG. 84 is a side cross-sectional view of the anvil assembly of thesurgical stapling device shown in FIG. 65;

FIG. 85 is a top cross-sectional view of the anvil assembly of thesurgical stapling device shown in FIG. 84;

FIG. 86 is a top view of the anvil center rod of the anvil assemblyshown in FIG. 85;

FIG. 87 is a side view of the anvil center rod of the anvil assemblyshown in FIG. 85;

FIG. 88 is a side cross-sectional view of the anvil head of the anvilassembly shown in FIG. 85;

FIG. 89 is a side view of the anvil head shown in FIG. 88;

FIG. 90 is a side cross-sectional view of the anvil center rod shown inFIG. 87;

FIG. 91 is a side view of the anvil cover of the anvil assembly shown inFIG. 84;

FIG. 92 is a side cross-sectional view of the anvil cover shown in FIG.91;

FIG. 93 is a side cross-sectional view of an anvil assembly insertionhandle;

FIG. 94 is a side perspective view of the anvil assembly insertionhandle shown in FIG. 93;

FIG. 95 is a side cross-sectional view of the anvil assembly insertionhandle attached to the anvil assembly shown in FIG. 84;

FIG. 96 is a top view of a speculum suitable for use with the presentlydisclosed surgical stapling device;

FIG. 97 is a side perspective view from above of the speculum shown inFIG. 96;

FIG. 98 is a rear view of the speculum shown in FIG. 96;

FIG. 99 is a side cross-sectional view of the speculum shown in FIG. 97;

FIG. 100 is a longitudinal cross-sectional view of a surgical staplingdevice including a ratchet mechanism disposed in a first open positionin accordance with another embodiment of the present disclosure;

FIG. 101 is a longitudinal cross-sectional view of the surgical staplingdevice of FIG. 100 disposed in a second approximated position;

FIG. 102 is a top view of the ratchet mechanism of FIGS. 100-101;

FIG. 102A is an enlarged view of the clip for the ratchet mechanism;

FIG. 103 is a longitudinal cross-sectional view of the ratchet mechanismof FIGS. 100-102 illustrated in its first open position;

FIG. 104 is a longitudinal cross-sectional view of the ratchet mechanismof FIGS. 100-102 illustrated between its first open position and itssecond approximated position;

FIG. 105 is a longitudinal cross-sectional view of the ratchet mechanismof FIGS. 100-102 illustrated in its second approximated position;

FIG. 106 is a perspective view of a rack of the ratchet mechanism ofFIGS. 100-102 in accordance with an embodiment of the presentdisclosure;

FIG. 107 is a longitudinal cross-sectional view of a trigger insert ofthe ratchet mechanism of FIGS. 100-102 in accordance with an embodimentof the present disclosure; and

FIG. 108 is a side view of a pawl of the ratchet mechanism of FIGS.100-102 in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the presently disclosed surgical stapling device will nowbe described in detail with reference to the drawings in which likereference numerals designate identical or corresponding elements in eachof the several views.

Throughout this description, the term “proximal” will refer to theportion of the instrument closest to the operator and the term “distal”will refer to the portion of the instrument farthest from the operator.

FIGS. 1 and 2 illustrate one embodiment of the presently disclosedsurgical stapling device shown generally as 10. Briefly, surgicalstapling device 10 includes a proximal handle assembly 12, an elongatedcentral body portion 14 including a curved elongated outer tube 14 a,and a distal head portion 16. Alternately, in some surgical procedures,e.g., the treatment of hemorrhoids, it is desirable to have asubstantially straight central body portion. The length, shape and/orthe diameter of body portion 14 and head portion 16 may also be variedto suit a particular surgical procedure.

Handle assembly 12 includes a stationary handle 18, a firing trigger 20,a rotatable approximation knob 22 and an indicator 24. Stationary handle18 may be formed from thermoplastic handle sections 18 a and 18 b, e.g.,polycarbonate, (FIG. 3) which together define a housing for the internalcomponents of handle assembly 12. Handle sections 18 a and 18 b may besecured together by sonic welding. Alternately, other known securementtechniques may be employed including screws, adhesives, snap-fitconnectors, etc. The internal components of handle portion 12 will bediscussed in detail below. In one embodiment, cushioned and/or resilientslip resistant portions such as a grip (not shown) can be fastened to orincluded as part of handle sections 18 a and 18 b and firing trigger 20.The slip resistant grip may be formed over handle sections 18 a and 18 band firing trigger 20 using an overmolding procedure and may be formedfrom Neoprene polychloroprene or rubber. Alternately, other suitable,e.g., elastomeric, materials and joining techniques may be employed. Apivotally mounted trigger lock 26 is fastened to handle assembly 12 andis manually positioned to prevent inadvertent firing of stapling device10. Indicator 24 is positioned on the stationary handle 18 and includesindicia, e.g., color coding, alpha-numeric labeling, etc., to identifyto a surgeon whether the device has been fired and/or when the device isready to be fired.

Head portion 16 includes an anvil assembly 30 and a shell assembly 31.Each of these assemblies will be discussed in detail below. Except whereotherwise noted, the components of surgical device 10 are formed fromthermoplastics including polycarbonates, and metals including stainlesssteel and aluminum. The particular material selected to form aparticular component will depend upon the strength requirements of theparticular component. For example, the anvil may be formed from a metal,such as stainless steel, and the stationary handle may be formed from athermoplastic such as polycarbonate. Alternately, other materials notlisted above, which can withstand sterilization procedures, may be usedto form components of stapling device 10 provided the materials aresuitable for surgical use and meet the strength requirements of theparticular component.

FIGS. 3-5 illustrate the internal components of handle assembly 12. Theinternal components include the proximal components of approximation andfiring mechanisms, a firing lockout mechanism and an indicator drivemechanism. FIGS. 6 and 7 illustrate the internal components of elongatedbody portion 14. These components include the distal components of theapproximation and firing mechanisms. Each of these mechanisms will bedisclosed in detail hereinbelow.

Approximation Mechanism

Referring to FIGS. 3-8, the approximation mechanism includesapproximation knob 22, a rotatable sleeve 33, a drive screw 32, firstand second screw extensions 34 and 36 (FIG. 6), and an anvil retainer38. Rotatable sleeve 33 includes a substantially cylindrical hollow bodyportion 40 and a substantially cylindrical collar 42 which togetherdefine a central bore 33 a. Collar 42 has an annular groove 44 formedthereabout and is dimensioned to receive an inwardly extending flange 46formed on an inner wall of stationary handle 18. Engagement betweengroove 44 and flange 46 axially fixes sleeve 33 within handle 18 whilepermitting rotation of sleeve 33 in relation to stationary handle 18.The proximal end of body portion 40 of rotatable sleeve 33 extendsthrough an opening 18 b in the proximal end of stationary handle 18. Apair of diametrically opposed elongated ribs 48 are positioned on theouter surface of body portion 40. Approximation knob 22 includes a pairof internal slots 49 a positioned to receive ribs 48 of sleeve 33 torotatably fix sleeve 33 to knob 22, such that rotation of knob 22 causesconcurrent rotation of sleeve 33.

The proximal half of screw 32 includes a helical channel 50 and isdimensioned to be slidably positioned within central bore 33 a ofrotatable sleeve 33. The distal end of screw 32 includes an annularrecess 35 dimensioned to receive a seal member 37 (FIG. 3) for providinga fluid tight seal between the outer surface of screw 32 and the innersurface of pusher link 74 (FIG. 6). A pin 52 (FIG. 3) extends radiallythrough body portion 42 of sleeve 33 into helical channel 50. Sincesleeve 33 is axially fixed with respect to stationary handle 18,rotation of sleeve 33 about screw 32 causes pin 52 to move along channel50 of screw 32 to effect axial movement of screw 32 within stationaryhandle 18.

The distal end of screw 32 includes a transverse slot 54. Top and bottomscrew extensions 34 and 36 (FIG. 6) each include a proximally locatedflexible flat band portion 58 and a distally located flat band portion60. Alternately, it is envisioned that screw extensions 34 and 36 mayhave other than a band configuration. For example, screw extensions 34and 36 may be semi-circular or circular in cross-section. Theflexibility of top and bottom screw extensions 34 and 36 permitsmovement of screw extensions 34 and 36 through curved elongated bodyportion 14. The proximal end of each band portion 58 includes a hole 62dimensioned to receive a pin 64 for securing the proximal end of screwextensions 34 and 36 within transverse slot 54 of screw 32. Alternately,other fastening techniques may be used to secure each band portion 58 toscrew 32, e.g., welding, crimping, etc. Distally located band portion 60of each screw extension 34 and 36 is dimensioned to be received within atransverse slot 66 formed in a proximal end of anvil retainer 38 (FIG.7) to fasten anvil retainer 38 to the distal end of screw extensions 34and 36. In one embodiment, a pair of pins 66 a which extend through theproximal end of anvil retainer 38 and band portions 60 are used tosecure screw extensions 34 and 36 to anvil retainer 38. Alternately,band portions 60 can be brazed or welded within slot 66 or otherfastening techniques may be used to secure band portions 60 of screwextensions 34 and 36 to anvil retainer 38, e.g., screws, crimping, etc.Anvil retainer 38 includes an annular protrusion 177 (FIG. 7) which isconfigured to engage the anvil assembly in a manner to be discussed indetail below. Alternately, protrusion 177 need not be annular or mayinclude different attachment structure, e.g., recesses, grooves, etc.

In operation, when approximation knob 22 is manually rotated, rotatablesleeve 33 is rotated about the proximal end of screw 32 to move pin 52along helical channel 50 of screw 32. Since sleeve 33 is axially fixedto stationary handle 18, as pin 52 is moved through channel 50, screw 32is advanced or retracted within stationary handle 18. As a result, topand bottom screw extensions 34 and 36, which are fastened to the distalend of screw 32, and anvil retainer 38, which is fastened to the distalend of screw extensions 34 and 36, are moved axially within elongatedbody portion 14. Since anvil assembly 30 is secured to the distal end ofanvil retainer 38, rotation of approximation knob 22 will effectmovement of anvil assembly 30 in relation to shell assembly 31 betweenspaced and approximated positions.

Firing Mechanism

Referring to FIGS. 3-6 and 9, the firing mechanism includes firingtrigger 20, a firing link 72 and an elongated pusher link 74 (FIG. 6).Firing trigger 20 includes a body portion 76 and a trigger cover 80. Acushioned gripping surface (not shown) which may be formed of Neoprenepolychloroprene or rubber is provided on trigger cover 80. The cushionedgripping surface provides a non-slip cushioned surface to make actuationof device 10 more comfortable and less traumatic to a surgeon. Bodyportion 76 of trigger 20 is pivotally connected to a coupling member 86(which is secured to the proximal end of pusher link 74), by a pivotmember 84. Coupling member 86 may be formed integrally with pusher link74 or as a separate element fastened thereto. Firing link 72 has a firstend pivotally secured to body portion 76 of trigger 20 by a pivot member87 and a second end pivotally secured within a vertical slot 82 formedbetween stationary handle half-sections 18 a and 18 b of stationaryhandle 18 by pivot member 79. Pivot member 79 is free to move verticallywithin slot 82. A spring 82 a (FIG. 9) is supported within handle 18 tourge pivot member 79 downwardly towards the bottom of slot 82. Bodyportion 76 further includes a pair of abutments including an abutment 89and an abutment 91 which are positioned to engage the distal end 26 a(FIG. 4) of trigger lock 26 in a manner to be described in greaterdetail below to prevent actuation of trigger 20 prior to approximationof device 10.

Coupling member 86 which is supported on the proximal end of elongatedpusher link 74 includes a flange 104 (FIG. 6). A spring 106, positionedbetween an inner wall or abutment within stationary handle 18 and flange104, biases pusher link 74 proximally to a retracted, non-firedposition. A pair of wings 108 extend radially outwardly from couplingmember 86. Wings 108 are dimensioned to slide along channel 111 (FIG. 3)formed along the internal walls of stationary handle 18 to maintainproper alignment of pusher link 74 within stationary handle 18 duringfiring of device 10.

The distal end of pusher link 74 includes a pair of engagement fingers110 which are dimensioned to lockingly engage with members 220 formed inthe proximal end of pusher back 186. Pusher back 186 forms part of shellassembly 31 and will be discussed in greater detail below. Pusher link74 may be formed from a flexible plastic material and includes aplurality of notches 187 which allow pusher link 74 to bend more easilyas it moves through body 14. Pusher link 74 defines a hollow channel 75for slidably receiving the approximation mechanism. A flat surface orcutout 74 a formed in pusher link 74 slidably supports screw extensions34 and 36 which are positioned in juxtaposed alignment one on top of theother. Spacers 77 are positioned within outer tube 14 a adjacent cutout74 a to provide additional support for screw extensions 34 and 36 andpusher link 74 and prevent each component from buckling duringactuation. An annular channel 74 b is formed about pusher link 74 toreceive an O-ring seal 74 c. Pusher link 74 is slidably positionedwithin body portion 14 such that O-ring 74 c seals the space betweenpusher link 74 and an internal wall of outer tube 14 a. Operation of thefiring mechanism of the device will be described in detail below.

When firing trigger 20 is actuated, i.e., pivoted about pivot member 84,firing link 72 is moved proximally until pivot member 79 engages anabutment surface 307 (FIGS. 25, 28 and 48) formed on screw stop 306.Screw stop 306 is axially fixed to screw 32. When firing trigger 20 ispushed distally, pusher link 74 is advanced distally against the bias ofspring 106. Turning again to FIG. 6, since the distal end of pusher link74 is connected to pusher back 186, actuation of firing trigger 20effects advancement of pusher back 186 within shell assembly 31 to ejectstaples from shell assembly 31 in a manner to be described below.

Anvil Assembly

Referring to FIGS. 10-21, anvil assembly 30 includes an anvil headassembly 120 and an anvil center rod assembly 152. Anvil head assembly120 includes a post 122, an anvil head 124, a backup plate 126, acutting ring 128, an anvil 129 and a retaining clip 127. Post 122 iscentrally positioned through a bore in anvil head 124. Anvil 129 issupported on anvil head 124 in an outer annular recess 136 and includesa plurality of pockets 140 for receiving and deforming staples. At leastone tab 129 a extends radially outwardly from anvil 129 and isdimensioned to be received within a cutout 124 a formed in anvil head124. Tab 129 a and cutout 124 a function to align anvil 129 withinannular recess 136. Backup plate 126 includes a central opening 126 bwhich is positioned about post 122 within an inner recess 134 of anvilhead 124 between post 122 and annular recess 136. Backup ring 126includes a raised platform 126 a. Cutting ring 128 includes an opening128 a having a configuration substantially the same as platform 126 a.Opening 128 a is positioned about platform 126 a to rotatably fixcutting ring 128 a on backup ring 126. In one embodiment, cutting ring128 is formed from polyethylene and is fixedly secured to backup plate126 using, for example, an adhesive. Backup ring 126 may be formed froma harder material such as a metal. Alternately other materials ofconstruction may be used to construct plate 126 and ring 128. Cuttingring 128 and backup plate 126 are slidably mounted about post 122.Backup plate 126 includes a pair of inwardly extending tabs 150 whichwill be described in further detail below. Cutting ring 128 includestabs 128 b which are received within cutouts 124 b formed in anvil head124 to properly align backup ring 126 and cutting ring 128 within anvilhead 124.

Anvil center rod assembly 152 includes anvil center rod 154, a plunger156 and plunger spring 158. A first end of center rod 154 includes atransverse throughbore 160 which is offset from the central longitudinalaxis of center rod 154. Post 122 of anvil head assembly 120 alsoincludes a transverse throughbore 162. A pivot member 164 pivotablysecures post 122 to center rod 154 such that anvil head assembly 120 ispivotably mounted to anvil center rod assembly 152. Plunger 156 isslidably positioned in a bore 154 b (FIG. 16) formed in the first end ofcenter rod 154. Plunger 156 includes an engagement finger 168 which isoffset from the pivot axis of anvil head assembly 120 and biased intoengagement with the base 122 a of post 122 by plunger spring 158 to urgeanvil head assembly 120 to a pivoted position orthogonal to center rod154. In a prefired position, tabs 150 formed on backup plate 126 engagea top surface 154 a (FIG. 20) of center rod 154 to prevent anvil headassembly 120 from pivoting about pivot member 164. As device 10 isfired, backup plate 126 and cutting ring 128 are moved deeper into anvilrecess 134 of anvil head 124 about post 122 (FIG. 21) by knife 188 (FIG.6) in a manner to be described in further detail below. Movement ofbackup plate 126 and cutting ring 128 into anvil recess 134 moves tabs150 out of engagement with top surface 154 a of center rod 154 to permitplunger 156 to pivot anvil head assembly 120 about pivot member 164.

A retainer clip 127 is positioned in a transverse slot 122 c formed inpost 122 and includes a pair of outwardly biased flexible arms 127 a and127 b. Arm 127 b includes a recess 127 c dimensioned to receive pivotpin 164 (FIG. 17). Prior to firing device 10, arms 127 a and 127 b aredeformed inwardly by backup plate 126 (FIG. 17). After device 10 hasbeen fired and backup plate 126 has been pushed deeper into anvil head124 by knife 188, flexible arms 127 a and 127 b spring outwardly to aposition in front of backup plate 126. In this position, arms 127 a and127 b prevent cutting ring 128 and backup plate 126 from sticking toknife 188 when anvil assembly 30 is unapproximated.

A second end of center rod 154 includes a bore 170 defined by aplurality of flexible arms 155. Bore 170 is dimensioned to receive aremovable trocar 157 (FIG. 12). Flexible arms 155 each include anopening 155 a dimensioned to receive a projection 157 d formed onremovable trocar 157 to releasably secure trocar 157 to center rod 154(FIG. 13). The distal ends of each of flexible arms 155 include aninternal shoulder 155 b dimensioned to releasably engage anvil retainer38 (FIG. 6) in a manner to be discussed in detail below. A plurality ofsplines 181 (FIG. 10) are formed about center rod 154 and aredimensioned to be received within grooves 196 a (FIG. 6) in shellassembly 31 to align anvil assembly 30 with shell assembly 31 duringapproximation of the anvil and shell assemblies. Center rod 154 alsoincludes an annular recessed portion 183 to facilitate grasping of anvilassembly 30 by a surgeon with a grasper.

Turning again to FIG. 12-15, removable trocar 157 includes a trocar tip157 a, a body portion 157 b and a cantilevered arm 157 c. Projection 157d is positioned on the end of cantilevered arm 157 c. Arm 157 c isdeflectable downwardly, i.e., radially inwardly, in the directionindicated by arrow “A” in FIG. 13 to facilitate insertion of bodyportion 157 b into bore 170 of center rod 154. Splines 157 e areprovided on body portion 157 b to properly align trocar 157 within bore170 of center rod 154. Arm 157 c biases projection 157 d outwardly suchthat when projection 157 d passes beneath opening 155 a in center rod154, projection 157 d snaps into opening 155 a to releasably secureremovable trocar 157 to center rod 154. A tab 157 f is positioned on arm157 c and can be depressed to facilitate removal of trocar 157 fromcenter rod 154. Trocar tip 157 a includes a throughbore 157 gdimensioned to receive a suture (not shown) to facilitate locating andremoval of trocar 157 within and from the human body. Althoughillustrated as having a sharpened tip, other trocar tip configurationsare envisioned, e.g., blunt.

Shell Assembly

Referring to FIG. 6, shell assembly 31 includes a shell 182, a pusherback 186, a cylindrical knife 188, and a staple guide 192. Shell 182includes an outer housing portion 194 and an inner guide portion 196having grooves 196 a for mating with splines 181 on anvil center rod 154(FIG. 10). Outer housing portion 194 defines a throughbore 198 having adistal cylindrical section 200, a central conical section 202 and aproximal smaller diameter cylindrical section 204. A plurality ofopenings 206 may be formed in conical section 202. Openings 206 aredimensioned to permit fluid and tissue passage during operation of thedevice. A pair of diametrically opposed flexible engagement members 207are formed on proximal cylindrical section 204 of shell 182. Engagementmembers 207 are positioned to be received in openings 207 a formed onthe distal end of outer tube 14 a to secure shell 182 to elongated body14. A pair of openings 211 formed in the proximal end of outer tube 14 aare dimensioned to receive protrusions (not shown) formed on theinternal wall of stationary handle 18 (FIG. 1) to facilitate attachmentof tube 14 a to handle portion 12.

Turning again to FIG. 6, pusher back 186 includes a central throughbore208 which is slidably positioned about inner guide portion 196 of shell182. Pusher back 186 includes a distal cylindrical section 210 which isslidably positioned within distal cylindrical section 200 of shell 182,a central conical section 212 and a proximal smaller diametercylindrical section 214. The proximal end of pusher back 186 includesmembers 220 which are configured to lockingly engage with resilientfingers 110 of pusher link 74 to fasten pusher link 74 to pusher back186 such that a distal face of pusher link 74 abuts a proximal face ofpusher back 186.

The distal end of pusher back 186 includes a pusher 190. Pusher 190includes a multiplicity of distally extending fingers 226 dimensioned tobe slidably received within slots 228 formed in staple guide 192 toeject staples 230 therefrom. Cylindrical knife 188 is frictionallyretained within the central throughbore of pusher back 186 to fixedlysecure knife 188 in relation to pusher 190. Alternately, knife 188 maybe retained within pusher back 186 using adhesives, crimping, pins, etc.The distal end of knife 188 includes a circular cutting edge 234.

In operation, when pusher link 74 is advanced distally in response toactuation of firing trigger 20, as will be described below, pusher back186 is advanced distally within shell 182. Advancement of pusher back186 advances fingers 226 through slots 228 of staple guide 192 toadvance staples 230 positioned within slots 228 and eject staples 230from staple guide 192 into staple deforming pockets 140 of anvil 129(FIG. 11). Since knife 188 is secured to pusher back 186, knife 188 isalso advanced distally to core tissue as will be described in moredetail below.

A rigid bushing 209 is supported in the proximal end of inner guideportion 196 of shell 182. Bushing 209 defines a throughbore dimensionedto slidably receive anvil retainer 38 and center rod 154 (FIG. 10) ofanvil assembly 30. Bushing 209 provides lateral support for flexiblearms 155 of center rod 154 when the anvil assembly 30 has beenapproximated to prevent disengagement of anvil assembly 30 from anvilretainer 38. In the unapproximated position, flexible arms 155 of centerrod 154 are positioned externally of bushing 209 to permit removal ofanvil assembly 30 from retainer 38.

Cam Adjustment Mechanism

Referring to FIGS. 8 and 22-28, a cam adjustment member 400 is securedby set screw 312 onto a sidewall 306 a of screw stop 306 within a recess306 b formed in sidewall 306 a. Cam adjustment member 400 includes acircular disc 402 having a throughbore 404. Throughbore 404 iseccentrically formed through disc 402 and is dimensioned to receive setscrew 312. A smaller notch or hole 406 is also formed in disc 402 and isdimensioned to receive the tip of an adjustment tool (not shown). Recess306 b (FIG. 22) includes a forward abutment shoulder or surface 306 c(FIG. 23) and a rear abutment surface 306 d and is dimensioned toreceive disc 402 such that the outer edge of disc 402 abuts forward andrear abutment surfaces 306 c and 306 d.

Set screw 312 extends through disc 402 and screw stop 306 and isreceived in a threaded bore 32 a in screw 32 to secure screw stop 306 inposition on screw 32. Cam adjustment member 400 functions to adjust theaxial position of screw stop 306 on screw 32. More specifically, setscrew 312 can be loosened to allow disc 402 to rotate within recess 306b of screw stop 306 while still remaining fixed to screw 32. Since disc402 is eccentrically mounted about screw 32 and engages forward and rearabutment surfaces 306 c and 306 d of recess 306 b, rotation of disc 402about fixed set screw 312 will urge screw stop 306 axially along screw32 to adjust the axial position of screw stop 306 on screw 32. Forexample, when disc 402 is rotated in a clockwise direction (as viewed inFIG. 28) identified by arrow “B”, screw stop 306 will be moved axiallyin relation to screw 32 in the direction indicated by arrow “C” inresponse to engagement between the outer edge of disc 402 and rearshoulder 306 d of recess 306 b. Conversely, when disc 402 is rotated ina counter-clockwise direction (as viewed in FIG. 27), identified byarrow “D”, screw stop 306 will be moved axially in relation to screw 32in the direction indicated by arrow “E” in response to engagementbetween the outer edge of disc 402 and forward shoulder 306 c of recess306 b.

When stapling device 10 is in a fully approximated position (as can beseen for instance in FIG. 65), i.e., anvil assembly 30, 640 and shellassembly 31, 605 are brought into juxtaposed alignment to define atissue receiving clearance, screw stop 306 (FIG. 47) abuts against bodyportion 42 of the rotatable sleeve 33, i.e., sleeve 33 functions as astop for the approximation mechanism. In this position, anvil assembly30 and shell assembly 31 are spaced slightly to define a tissuereceiving clearance. By providing cam adjustment member 400, the tissuereceiving clearance can be selectively adjusted to be within a desiredrange by adjusting the position of screw stop 306 on screw 32. In oneembodiment, cam adjustment member 400 permits adjustment of the tissuereceiving clearance of ±0.045 inches, although greater or lesseradjustment capabilities are also envisioned. Typically, adjustments tothe tissue receiving clearance will be made by the device manufacturer.Alternately, a hole or opening (not shown) may be provided in handleportion 12 (FIG. 1) to provide direct access to adjustment member 400 toallow for adjustment of the tissue receiving clearance at the surgicalsite.

Indicator Mechanism

Referring to FIGS. 3-5, 9, 22, 29 and 33, the indicator mechanismincludes indicator 24, lens cover 24 a and slide member 500. Indicator24 is pivotally supported about a pivot member 502 which may be formedmonolithically with handle sections 18 a and 18 b. Lens cover 24 a ispositioned above indicator 24 and may be formed of magnificationmaterial to facilitate easy visualization of indicator 24. Slide member500 (FIG. 29) includes a body portion 504 having an elongated slot 506formed therein, a distal abutment member or upturned lip portion 508,and a proximal extension 510. Slide member 500 is slidably positionedbetween handle sections 18 a and 18 b. Proximal extension 510 isslidably supported within stationary handle 18 by support structure 516(FIG. 5). A biasing member 512, e.g., a coil spring, is positioned incompression about proximal extension 510 between support structure 516and body portion 504 of slide member 500 to urge slide member 500distally within stationary handle 18. Indicator 24 includes a pair ofdownwardly extending projections 518 and 520 positioned about pivotmember 502. Upturned lip portion 508 of slide member 500 is positionedbetween projections 518 and 520 and is positioned to engage projections518 and 520 as it moves within stationary handle 18. In the unfiredposition of device 10, biasing member 512 urges slide member 500distally to move lip portion 508 into engagement with projection 518 topivot indicator to a first position, which provides indication to asurgeon that the device has not been approximated and is not in afire-ready condition.

As discussed above, screw stop 306 is fixedly attached to screw 32.Screw stop 306 includes a first engagement member 522 which ispositioned to travel through slot 506 and engage the proximal end 506 aof slot 506 during approximation of the device. When engagement member522 abuts proximal end 506 a (FIG. 29) of slot 506, furtherapproximation of device 10 moves slide plate 500 proximally withinstationary handle 18 against the bias of spring 512 such that upturnedlip 508 of slide member 500 engages projections 518 & 520 of indicator24. (See FIG. 48). Engagement between projections 518 & 520 and lip 508causes indicator 24 to pivot about pivot member 502 to a secondposition. In the second position, indicator 24 provides indication to asurgeon that the device has been approximated and is now in a fire-readyposition.

Fire-Lockout Mechanism

Referring to FIGS. 3-5, 22, 30, 33, and 47, the firing-lockout mechanismincludes trigger lock 26 and lockout member 530. Trigger lock 26 ispivotally supported within bores 532 in handle sections 18 a and 18 babout pivot member 534. In one embodiment, pivot member 534 extends froman upper edge of trigger lock 26 and is T-shaped and frictionallyengages the inner wall of bores 532 to prevent free rotation of triggerlock 26. Tip 26 a (FIG. 5) of trigger lock 26 is positioned betweenabutments 89 and 91 on body portion 76 of firing trigger 20 to preventactuation of trigger 20 when trigger lock 26 is in the locked position.Trigger lock 26 also includes a proximal extension 26 b (FIG. 4) whichwill be discussed in further detail below.

Lockout member 530 (FIG. 30) includes a body portion 536, a proximalextension 538, a pair of front legs 540 a, a pair of rear legs 540 b,and an abutment member or downturned lip portion 542. Lockout member 530is slidably positioned between first and second stops 544 and 546 (FIG.5) formed on an internal wall of handle sections 18 a and 18 b. Stop 544is positioned to engage rear legs 540 b and stop 546 is positioned toengage front legs 540 a. It is also envisioned that a single abutmentmember may be substituted for each pair of legs. A biasing member 548,e.g., a coil spring, is positioned between stop 544 and body 536 aboutproximal extension 538 to urge lockout 530 to its distal-most positionwith legs 540 a abutting stop 546. In this position, extension 26 b oftrigger lock 26 is positioned beneath lip portion 542 of lockout member530 to prevent pivotal movement of trigger lock 26, and thus preventactuation of stapling device 10.

As discussed above and as shown in FIG. 47, screw stop 306 is secured toscrew 32. A second engagement member or members 548 extend downwardlyfrom screw stop 306. (See FIG. 22). When stapling device 10 isapproximated and screw 32 is moved proximally within stationary handle18, engagement member 548 abuts front legs 540 a of lockout member 530to move lockout member 530 proximally against the bias of member 548 toa position in which lip portion 542 is spaced proximally of extension 26b of trigger lock 26. In this position of lockout member 530, triggerlock 526 can be pivoted to permit firing of stapling device 10.

Tactile Indicator Mechanism

Referring to FIGS. 3, 5, 9 and 9A, a tactile indicator mechanismprovided in stationary handle 18 includes an abutment member 580 whichis slidably positioned in a vertical slot 582 defined within handlesections 18 a and 18 b. Abutment member 580 includes a protuberance 580a and a guide rib 580 b. Protuberance 580 a is dimensioned to bereceived within one of two detents 582 a and 582 b formed along a wallof slot 582. Abutment member 580 is movable from a retracted (downward)position, wherein protuberance 580 a is positioned within detent 582 a,to an extended (upward) position, wherein protuberance 580 a ispositioned within detent 582 b. Engagement between protuberance 580 aand detents 582 a and 582 b retains abutment member 580 in therespective position. Detent 582 c, formed in vertical slot 582, is sizedto slidably receive guide rib 580 b and thereby maintain member 580 incontact with slot 582.

Prior to firing of stapling device 10, abutment member 580 is located inthe retracted (downward) position (FIG. 5). When device 10 is fired, anextension 590 of firing link 72 engages abutment member 580 and movesabutment member 580 from its retracted to its extended position. In theextended position, abutment member 580 extends into channel 111 ofstationary handle 18.

Screw stop 306 includes a pair of wings 584 which are slidablypositioned in channel 111 of stationary handle 18. After stapling device10 has been fired, abutment member 580 is positioned within channel 111.During unapproximation of anvil assembly 150 and cartridge assembly 31,one of the wings 584 of screw stop 306 engage abutment member 580 whenthe device has been unapproximated a sufficient distance to allow anvilassembly 30 to pivot to its reduced profile position (as will bediscussed in mere detail below and as can be seen in FIG. 57).Engagement between abutment member 580 and wing 584 of screw stop 306provides a tactile and/or an audible indication to the surgeon that theanvil assembly 120 has tilted and stapling device 10 can be removed froma patient. If the surgical stapling device is unapproximated further,wing 584 will force abutment member 580 from the extended position backto the retracted position.

Operation

Operation of surgical stapling device 10 will now be described in detailwith reference to FIGS. 31-61.

FIGS. 31-35 illustrate surgical stapling device 10 in the unapproximatedor open position prior to attachment of anvil assembly 30 to anvilretainer 38. In this position, biasing member 106 is engaged withcoupling 86 to urge pusher link 74 to its proximal-most position inwhich coupling 86 abuts screw-stop 306. Biasing member 512 is engagedwith slide member 500 of the indicator mechanism to position slidemember 500 in engagement with projection 518 of indicator 24 to pivotindicator 24 in a clockwise direction, as viewed in FIG. 33. Biasingmember 549 is engaged with body 536 of lockout member 530 to urgelockout member 530 to its distal-most position, wherein lip portion 542of lockout member 530 is positioned above extension 26 b of trigger lock26 to prevent movement of trigger lock 26 to the unlocked position.Biasing member 82 a engages pivot member 79 to urge pivot member 79 tothe base of vertical slot 82. Tactile indicator 580 is in the retractedor downward position with protrusion 580 a positioned with detent 582 a.

FIGS. 36-44 illustrate surgical stapling device 10 with anvil assembly30 attached to anvil retainer 38 and the anvil assembly 30 in theunapproximated or open position. Referring to FIGS. 37 and 38, duringattachment of anvil assembly 30 to anvil retainer 38, anvil retainer 38is positioned within bore 170 of center rod 154 of anvil assembly 30.Flexible arms 155 deflect outwardly to accommodate center rod 154.Center rod 154 is advanced onto anvil retainer 38 in the directionindicated by arrow “K” in FIG. 37 until internal shoulder 155 b offlexible arms 155 passes over annular protrusion 177 formed on anvilretainer 38. At this point, resilient legs 155 releasably engage theanvil retainer. The position of the remaining components of staplingdevice are unaffected by attachment of anvil assembly 30 to anvilretainer 38 and remain as described above and shown in FIGS. 31-35.

FIGS. 45-50 illustrate surgical stapling device 10 during movement ofanvil assembly 30 and cartridge assembly 31 to the approximated orclosed position. As discussed above, anvil assembly 30 is moved to theapproximated or closed position by rotating rotation knob 22 in thedirection indicated by arrow “L” in FIG. 45. Rotation of knob 22 causescylindrical sleeve 33 to rotate to move pin 52 along helical channel 50of screw 32. Movement of pin 52 (FIG. 48) along helical channel 50causes screw 32 to translate within sleeve 33. The distal end of screw32 is connected to screw extensions 34 and 36 which are fastened attheir distal ends to anvil retainer 38. As such, retraction of screw 32within sleeve 33 is translated into proximal movement of anvil retainer38 and anvil assembly 30. It is noted that when anvil assembly 30 isapproximated, flexible legs 155 of center rod 154 are drawn into bushing209 to lock legs 155 onto anvil retainer 38. (See FIG. 46).

As discussed above, screw stop 306 (FIG. 47) is axially fixed to screw32 by set screw 312. Thus, as screw 32 is retracted within sleeve 33,screw stop 306 is moved from a distal position within stationary handle18 to a proximal position. As screw stop 306 moves from the distalposition to the proximal position, first engagement member 522 formed onscrew stop 306 abuts proximal end 506 a of slot 506 of slide plate 500and moves slide plate 500 proximally against the bias of spring 512. Asslide plate 500 moves proximally, lip 508 of slide member 500 engagesprojections 518 & 520 of indicator 24 to pivot indicator 24 in acounter-clockwise direction as viewed in FIG. 48.

Screw stop 306 also includes a second engagement member 548 (FIG. 47).As screw stop 306 is moved from the distal position to the proximalposition during approximation of anvil assembly 30, second engagementmember 548 engages distal legs 540 a of lockout member 530 to movelockout member 530 proximally to a position in which lip portion 542 isspaced proximally of extension 26 b of trigger lock 26. In thisposition, trigger lock 26 can be pivoted to an unlocked position topermit firing of stapling device 10.

Movement of screw stop 306 to its proximal-most position withinstationary handle 18 positions abutment surface 307 (FIG. 48) of screwstop 306 in position to engage pivot member 79 of firing link 72.Abutment surface 307 comprises a substantially concave surface which ispositioned to partially capture and act as a backstop for pivot 79during firing of the stapling device.

FIGS. 51-56 illustrate surgical stapling device 10 during the firingstroke of firing trigger 20. As trigger 20 is compressed towardsstationary handle 18 (as shown by the arrow in FIG. 51), pivot member 79engages abutment surface 307 on screw stop 306 and firing trigger 20 ispushed distally. As discussed above, the distal end of firing trigger 22is connected through coupling member 86 to the proximal end of pusherlink 74. Accordingly, as firing trigger 20 is moved distally, pusherlink 74 is moved distally to effect advancement of pusher back 186within shell assembly 31. Fingers 190 of pusher back 186 engage andeject staples 230 from staple guide 192 (FIG. 52).

Cylindrical knife 188 is moved concurrently with pusher back 186 suchthat knife 188 moves into engagement with cutting ring 128 and backupplate 126. As discussed above, cutting ring 128 may be formed frompolyethylene and backup plate 126 may be formed from a metal. When knife188 engages cutting ring 128, it cuts into cutting ring 128 and pushesbackup plate 126 deeper into anvil head 124 to move tabs 150 fromengagement with top surface 154 a of center rod 154 (FIG. 56). Anvilhead 124 is now free to pivot about member 164 and is urged to do so byplunger 156. It is noted that because the anvil assembly is injuxtaposed alignment with shell assembly 31, the anvil head 14 will notpivot fully until the anvil and shell assemblies have beenunapproximated a distance sufficient to allow the anvil head to fullypivot. When backup plate 126 moves into anvil head 124, flexible arms127 a and 127 b of retainer clip 127 spring outwardly to a position infront of backup plate 126 blocking movement of backup plate 126 out ofanvil head 124 (FIG. 55). As discussed above, arms 127 a and 127 bprevent backup plate 126 from sticking to knife 188 when anvil assembly30 is returned to the unapproximated position.

Referring to FIGS. 57-60, during unapproximation of stapling device 10after device 10 has been fired, wing 584 of screw stop 306 engagestactile indicator 580 (FIG. 58) at the point of unapproximation at whichanvil assembly 124 is able to pivot to its tilted reduced profileposition. Contact between wing 584 and tactile indicator 580 provides atactile and/or audible indication that anvil head 124 has tilted. Ifadditional force is provided to approximation knob 22, wing 584 of screwstop 306 will force tactile indicator to the retracted position to allowstapling device 10 to move to the fully open position. In this position,flexible arms 155 are positioned distally of bushing 209 and anvilassembly 30 can be disengaged from anvil retainer 28.

FIGS. 62-91 illustrate another embodiment of the presently disclosedsurgical stapling device shown generally as 600. Stapling device 600 isconfigured and dimensioned to be particularly suitable for use insurgical procedures for removing internal hemorrhoids from a patient.Briefly, surgical stapling device 600 includes a proximal handleassembly 601, a central body portion 603 and a distal head portion 605.The handle assembly 601 is substantially identical to handle assembly 12of surgical stapling device 10 and will not be discussed in furtherdetail herein.

Referring to FIGS. 62-71, the approximation mechanism of surgicalstapling device 600 includes an approximation knob 602, a rotatablesleeve 604, a drive screw 606, a retainer extension 608, and an anvilretainer 610. Approximation knob 602, rotatable sleeve 604 and drivescrew 606 are substantially identical to the like named componentsdescribed above with respect to surgical stapling device 10 and will notbe described in further detail herein. Referring to FIGS. 66-68,retainer extension 608 includes a proximal end 612 defining a bore 614dimensioned to receive the distal end of drive screw 606. A pair oftransverse openings 618 extend through sidewalls of the proximal end ofretainer extension 608 to facilitate attachment of retainer extension608 to the distal end of drive screw 606 with a pin or screw 620 (FIG.62). Alternately, other known attachment devices may be used, e.g.,welding, brazing, screw threads, etc. The distal end of retainerextension 608 includes a flat finger 622 configured to be receivedwithin a slot 624 (FIG. 69) formed in the proximal end of anvil retainer610. Openings 626 and 626 a in retainer extension 608 and anvil retainer610 (FIG. 70), respectively, are dimensioned to receive pins or screws628 (FIG. 62) to secure anvil retainer 610 to the distal end of retainerextension 608. Alternately, other attachment configurations andtechniques are contemplated.

Referring also to FIGS. 69-71, anvil retainer 610 includes an elongatedreduced diameter distal extension 630 and a central annular shoulder632. In one embodiment, annular shoulder 632 defines an angle of aboutninety-degrees with respect to the outer axial surface 610 a of anvilretainer 610 (FIG. 71). As will be discussed in further detail below,the sharp angle of shoulder 632 securely fastens an anvil assembly ontoanvil retainer 610. As discussed above with respect to stapling device10, when approximation knob 602 (FIG. 62) is manually rotated, rotatablesleeve 604 is rotated about the proximal end of screw 606 to advance orretract screw 606 within handle assembly 601. Since the proximal end 612of retainer extension 608 is fastened to the distal end of screw 606 andthe proximal end of anvil retainer 610 is fastened to the distal end ofretainer extension 608, retainer extension 608 and anvil retainer 610will move axially within central body portion 603 when drive screw 606moves axially within handle assembly 601. As will be discussed infurther detail below, an anvil assembly 640 (FIG. 64) is secured toanvil retainer 610. Accordingly, when approximation knob 602 is manuallyrotated, anvil assembly 640 will move axially with anvil retainer 610 inrelation to a shell assembly 642 between spaced and approximatedpositions.

As illustrated in FIGS. 62-64, distal head portion 605 (FIG. 63)includes anvil assembly 640 and shell assembly 642. Shell assembly 642includes a housing 644, a pusher 646, a cylindrical knife 645 and astaple guide 648. Referring also to FIGS. 72-79, housing 644 includes anouter housing portion 644 a and an inner guide portion 644 b. Outerhousing portion 644 a (FIGS. 72-75) defines an outwardly divergingthroughbore 650 and includes a small diameter proximal end 652 and alarge diameter distal end 654. Distal end 652 includes a pair ofdiametrically opposed spring tabs 656 for releasably engaging innerguide portion 644 b in a manner to be discussed below. Throughbore 650is dimensioned to slidably receive pusher 646 (FIG. 62). Because of theconfiguration of throughbore 650 and pusher 646, pusher 646 is slidablein throughbore 650 only in a distal direction. A pair of stabilizingribs 653 (FIG. 75) extend inwardly from an inner wall definingthroughbore 650. Stabilizing ribs 653 engage ribs 654 (FIG. 76) formedon sidewalls of inner guide portion 644 b to secure inner guide portion644 b within outer housing portion 644 a.

Inner guide portion 644 b (FIGS. 76-79) includes a cylindrical proximalend 658, a cylindrical central portion 660 and an inner distal portion662. Proximal end 658 includes a pair of openings 664 for engagingspring tabs (not shown) formed on handle assembly 612 for securing shellassembly 642 onto handle assembly 612. Ribs 654 are formed on innerdistal portion 662 of inner guide portion 644 b. A pair of annular ribs666 are formed in spaced relation on central portion 660. Spring tabs656 of outer housing portion 644 a (FIGS. 72-75) are positioned to snapfit into the space between ribs 666 to secure inner guide portion 644 bto outer housing portion 644 a. Inner distal portion 662 defines acylindrical bore 668 for slidably receiving retainer extension 608 andanvil retainer 610 (FIG. 62). Cylindrical bore 668 includes an annulararray of ribs and grooves 676 for accurately circumferentially andaxially aligning anvil assembly 640 and shell assembly 642 duringapproximation thereof. The proximal end of distal portion 662 extendsproximally within central portion 660 to define therewith a pair ofchannels 670 (FIG. 78). A proximal portion of channels 670 isdimensioned to slidably receive drive arms of a pusher link (not shown).The pusher link employed in this embodiment is similar to pusher link 74discussed above with respect to stapling device 10 and will not bediscussed in further detail herein.

Referring to FIGS. 62 and 80-83, pusher 646 is slidably positionedwithin shell assembly housing 644. Pusher 646 includes a pair ofproximal extensions 676 which extends through the distal end of channels670 (FIG. 78) formed in inner guide portion 644 b. The distal end ofpusher 646 includes a multiplicity of distally extending fingers 680which are slidably received within slots formed in staple guide 648(FIG. 62). Staple guide 648 is fixedly retained in the distal end ofouter housing portion 644 a. Staples (not shown) are housed within thestaple guide slots (not shown). Movement of pusher 646 distally withinouter housing portion 644 a ejects staples from the slots of stapleguide 648. A cylindrical knife 645 (FIGS. 62 and 63) is secured orfrictionally retained within a central throughbore of pusher 646. Thedistal end of knife 645 includes an annular cutting edge 682. The distalportion of pusher 646 defines an internal chamber 780 for receivingexcised tissue.

Referring to FIGS. 84-89, anvil assembly 640 includes an anvil headassembly 684 and an anvil center rod 686. Anvil head assembly 684includes an anvil head 688, an anvil post 690, an anvil 692 and an anvilcover 694. Anvil cover 694 (FIGS. 91 and 92) is substantially conicaland includes a rounded distal portion 696 to facilitate smooth entry ofanvil assembly 640 into a body lumen or orifice, e.g., anus. Anvil 692is secured to anvil head 688 and includes a plurality of stapledeforming pockets (not shown), as discussed above, for receiving anddeforming staples. Anvil head assembly 684 is secured to the distal endof anvil center rod 686. Although anvil head assembly 684 may bepivotally secured to anvil center rod 686, as discussed above, in oneembodiment, anvil head assembly 684 is fixedly secured to anvil centerrod 686.

As illustrated in FIGS. 86 and 87 and 90, anvil center rod 686 defines acentral bore 700 which is partially defined by a plurality of flexilearms 702. Central bore 700 extends substantially along the longitudinallength of center rod 686. The distal end of each flexible arm 702includes a radial projection 702 a. Central bore 700 is dimensioned toslidably receive anvil retainer 610 (FIG. 62) including distal extension630 such that radial projections 702 a snap over and engage annularshoulder 632 (FIGS. 70 and 71) of anvil retainer 610 to secure anvilassembly 640 to anvil retainer 610. Radial projection 702 a (FIG. 90)defines a perpendicular surface which abuts shoulder 632 to securelyfasten anvil assembly 640 to anvil retainer 610 and substantiallyprevent inadvertent disengagement of anvil assembly 640 from anvilretainer 610. When anvil assembly 640 is secured to anvil retainer 610,distal extension 630 of anvil retainer 610 extends through central bore700 along a substantial portion of the length of anvil center rod 686.In one embodiment, distal extension 630 extends through central bore 700substantially the entire length of anvil center rod 686.

In use, when approximation knob 602 (FIG. 63) is manually rotated tomove screw 606 proximally, anvil retainer 610 and anvil assembly 640 arewithdrawn into shell assembly 642 to move anvil head assembly 684 intoapproximation with shell assembly 642 (FIG. 65). When flexible arms 702are drawn into cylindrical bore 668 of inner guide portion 644 b, arms702 are prevented from flexing outwardly to lock anvil assembly 640 toanvil retainer 610.

As discussed above, stapling device 600 is particularly suitable for usein surgical procedures for removing internal hemorrhoids from a patient.During such a procedure, anvil assembly 640 (FIG. 64) is inserted intothe anus and rectum of the patient independently of stapling device 600.Referring to FIGS. 93-95, an insertion handle 720 may be used tofacilitate insertion of anvil assembly 640 into the anus and rectum. Inone embodiment, handle 720 includes a gripping knob 722, a rigid shaft725 extending distally from knob 722 and an attachment portion 724.Attachment portion 724 includes a detent 726 and a protrusion 728.Attachment portion 725 of shaft 724 is dimensioned to be slidablyreceived within anvil center rod central bore 700. Detent 726 ispositioned to be received within one of a plurality of suture holes 730(FIG. 87) formed in the distal end of anvil center rod 686 to releasablylock handle 720 to anvil center rod 686. Protrusion 728 is positioned tobe slidably received between and engaged by flexible arms 702 toproperly align handle 720 with anvil center rod 686. A stop member 728 amay also be provided on the attachment portion to limit the insertiondepth of shaft 724 into central bore 700. To remove handle 720 fromanvil center rod 686, a force sufficient to flex flexible arms 702outwardly must be applied to handle 720 to release detent 726 fromsuture hole 730. In one embodiment, after anvil assembly 640 has beenproperly positioned in the anus and rectum, a purse string suture isplaced into each of the internal hemorrhoids. Thereafter, the pursestring is cinched about the anvil center rod 686 to draw the internalhemorrhoids inwardly about the anvil center rod 686.

Referring to FIGS. 96-99, in an alternate embodiment, the purse stringsuture may be placed into the internal hemorrhoids prior to insertion ofthe anvil assembly into the anus and rectum. Using either embodiment, ananoscope or speculum 750, may be provided to place the purse string intothe internal hemorrhoids. Speculum 750 may include a semi-cylindricalbody 752 having a tapered or blunt tip 754. Body 752 defines a channelor recess 756. The proximal end of body 752 has a semi-annular flange758 including a plurality of openings 760 and a pair of protrudingfinger tabs 762. Fingers tabs 762 and openings 760 allow for easiergripping and manipulation of the speculum during use. It is alsoenvisioned that speculum 750 may be formed from a clear plastic materialto enhance visualization. Further, the speculum 750 may includegradation markings (not shown) along the surface of the speculum 750 toassist the surgeon with knowledge of depth of placement of thehemorrhoids.

In use, blunt tip 754 of speculum 750 is inserted into the anus to aposition in which first internal hemorrhoids hang into channel 756. Apurse string suture is placed into a first portion of internalhemorrhoids. Speculum 750 is then rotated using finger tabs 762 andopenings 760 until a second portion of internal hemorrhoids hang intochannel 756. A purse string suture is placed into the second internalhemorrhoids. This process is repeated until a purse string suture hasbeen placed into each of the internal hemorrhoids about the annulus ofthe anus.

When a purse string suture has been placed into each of the internalhemorrhoids, speculum 750 is removed from the anus and the anvilassembly 640 is inserted into the anus and rectum. Thereafter, the pursestring sutures are cinched to draw the internal hemorrhoids in about theanvil center rod 686. Attachment structure such as openings, grooves,hooks, ridges or ribs, may be provided on anvil center rod 686 to securethe purse string suture and, thus, the internal hemorrhoids to the anvilcenter rod 686. It is also envisioned that the attachment structure maybe in the form of an axially adjustable member, e.g., slidable hook,which may be adjusted to change the position of the purse string sutureon anvil center rod 686 and within shell assembly 642. Likewise,gradations can be placed on the center rod 686 to indicate depth ofinsertion of the center rod 686 or length of the suture or of suturedhemorrhoids.

After the internal hemorrhoids have been cinched about anvil center rod686, center rod 686 is attached to anvil retainer 610 in the mannerdiscussed above. Distal extension 630 and anvil center rod 686 should beof a length to allow telescoping of extension 630 within anvil centerrod 686 before visibility of the surgical site is obstructed by shellassembly 642 of device 600. In one embodiment, the combined length ofanvil center rod 686 and retainer extension 630 is at least 4.5 inches(114.3) or of a length to achieve the above objective. By providing anextension on anvil retainer 610 and/or providing an elongated anvilcenter rod 686, visibility at the surgical site is greatly improved.Improved visibility not only simplifies attachment of anvil assembly 640to anvil center rod 686 but improves visibility during approximation ofanvil to ensure that the hemorrhoidal tissue is properly positionedabout the anvil shaft.

After the anvil assembly has been attached to the anvil center rod 686,knob 602 can be manually rotated to approximate the anvil and shellassemblies and draw the internal hemorrhoids into an inner chamber 780(FIG. 62) defined within pusher 646 and within annular knife 682 ofshell assembly 642. Firing trigger 790 (FIG. 62) can now be actuated inthe manner discussed above with respect to stapling device 10 to staple,sever and allow removal of the internal hemorrhoids. Thereafter,stapling device 600 is removed from the anus with the excised internalhemorrhoids contained within inner chamber 780 of shell assembly 642.

FIGS. 100-108 illustrate another embodiment of the presently disclosedsurgical stapling device shown generally as 1000. Surgical staplingdevice 1000 includes a housing 1010, an elongated portion 1020, an endeffector 1030, a movable handle 1040 and a ratchet mechanism 1050.Housing 1010 is substantially identical to handle assembly 12 ofsurgical stapling device 10 and handle assembly 601 of surgical staplingdevice 600 and will not be discussed in further detail herein.

With reference to FIGS. 100 and 101, elongated portion 1020 extendsdistally from housing 1010 and at least a portion of end effector 1030is disposed in mechanical cooperation with a distal portion 1022 ofelongated portion 1020. End effector 1030 in the illustrated embodimentincludes an anvil assembly and a shell assembly, the anvil assemblybeing moved into approximation with the shell assembly of distal portion1022 by the approximation mechanisms described above. Movable handle1040 is disposed in mechanical cooperation with housing 1010 and ismovable between a first open position (FIGS. 100 and 103) and a secondapproximated position (FIGS. 101 and 105) for affecting a function ofend effector 1030. Ratchet mechanism 1050 is disposed in mechanicalcooperation with movable handle 1040 and is configured to substantiallyprevent movable handle 1040 from moving towards its first open position(in the general direction of arrow “M” in FIG. 105) until movable handle1040 reaches a predetermined position. This predetermined position in apreferred embodiment corresponds to full firing of the stapler, e.g.firing of all the staples and full distal translation of the knife, ifprovided, although other predetermined positions are also contemplated,such as the commencement of firing of at least one staple. Thus, ratchetmechanism 1050 helps prevent movable handle 1040 from being prematurelyopened, e.g., before staples have been fired and/or before a knifesevers tissue. Accordingly, ratchet mechanism 1050 ensures a fullerfiring stroke is performed before movable handle 1040 can be opened.

Details of ratchet mechanism 1050 are further illustrated in FIGS.102-108. Ratchet mechanism 1050 includes a rack 1060, a pawl 1070 and aspring 1080. Rack 1060 is disposed in mechanical cooperation withhousing 1010 and includes rack teeth 1062 and a cam surface 1064. Pawl1070 is disposed in mechanical cooperation with movable handle 1040 andincludes pawl teeth 1072. Rack teeth 1062 and pawl teeth 1072 areconfigured for engagement with one another. Spring 1080, e.g., acompression spring, is disposed in mechanical cooperation with movablehandle 1040 and is configured to bias at least one of rack 1060 and pawl1070 towards the other such that rack teeth 1062 and pawl teeth 1072engage one another. In the illustrated embodiments, spring 1080 biasespawl 1070 in the direction of arrow “N” (FIG. 103) towards rack 1060.Cam surface 1064 of rack 1060 is configured to disengage rack teeth 1062and pawl teeth 1072 upon contact between cam surface 1064 and pawl 1070by urging pawl 1070 away from rack 1060 to facilitate movement ofmovable handle 1040 back towards its first open position.

With reference to FIGS. 102-105, a trigger insert 1090 is shown. Triggerinsert 1090 may be integrally formed with movable handle 1040, attachedto movable handle 1040 or may be insertable therewith. Trigger insert1090 is pivotably coupled to housing 1010, e.g., via a pin 1092 (FIGS.102-103) disposed through an opening 1094 on trigger insert 1090 andthrough an opening (not explicitly shown) of housing 1010, for instance.

A link 1100 is disposed in mechanical cooperation with housing 1010 andtrigger insert 1090. Link 1100 is illustrated pivotably coupled tohousing 1010, e.g., via a pin 1102 disposed through an opening 1104 on afirst portion 1105 of link 1100 and through an opening (not explicitlyshown) of housing 1010. Additionally, link 1100 is pivotably coupled totrigger insert 1090, e.g., via a pin 1107 disposed through an opening1108 on a second portion 1109 of link 1100 and through an opening 1095(FIG. 107) of trigger insert 1090.

Rack 1060, illustrated in FIGS. 103-106, is disposed adjacent secondportion 1109 of link 1100. Additionally, rack 1060 is configured toengage second portion 1109 of link 1100 and may be secured to link 1100via pins 1066 a, 1066 b extending through bores of rack 1060 and/or link1100. Accordingly, rack 1060 is pivotably movable with respect totrigger insert 1090 (and movable handle 1040). As such, movement ofmovable handle 1040 from its first open position (FIGS. 100 and 103) inthe direction of arrow “P” (FIG. 103) towards its second approximatedposition (FIGS. 101 and 105) causes rack 1060 to move in the generaldirection of arrow “Q” (FIG. 103) with respect to pawl 1070.

Pawl 1070 is illustrated in FIGS. 103-105 and 108 and is translatablewith respect to trigger insert 1090 via slots 1074 in pawl 1070 andbosses 1096 in trigger insert 1090. Moreover, as can be appreciated, thewidth of slots 1074 dictate the boundaries of movement between pawl 1070and trigger insert 1090. In the illustrated embodiments, pawl 1070includes a spring hub 1076 for facilitating alignment with a proximalportion 1082 of spring 1080. A distal portion 1084 of spring 1080 isbound by a distal portion 1098 of trigger insert 1090. Thus, spring 1080biases pawl 1070 proximally towards rack 1060, such that pawl teeth 1072engage rack teeth 1062.

In operation, when movable handle 1040 is in its first open position(FIGS. 100 and 103), rack teeth 1062 are engaged with pawl teeth 1072.As movable handle 1040 is moved through the firing stroke in thedirection of arrow “P” towards its second approximated position (FIG.104 illustrates movable handle 1040 between its first open position andits second approximated position), rack teeth 1062 continue to engagepawl teeth 1072. As can be appreciated with reference to FIG. 104, whenmovable handle 1040 is between its first open position and its secondapproximated position, the engagement of rack teeth 1062 and pawl teeth1072 substantially prevent movable handle 1040 from moving in thedirection of arrow “M” towards its first open position.

When movable handle 1040 has reached a predetermined position,illustratively the full firing stroke position, cam surface 1064 of rack1060 engages pawl 1070 and translates pawl 1070 distally in thedirection of arrow “R” (FIG. 105). When pawl 1070 is in its distallocation (FIG. 105), movable handle 1040 is able to return to its firstopen position (either automatically, manually or spring-assisted), asrack teeth 1062 and pawl teeth 1072 are not engaged with one another.

Clip or latch 1110 is disposed in mechanical cooperation with spring1080 and/or pawl 1070 and maintains pawl 1070 in a distal position afterfiring of the fasteners. More specifically, the bent down tab 1113(FIGS. 102A and 105) of latch 1110 engages a notch on pawl 1070. Opening1111 receives the spring hub 1076 of pawl 1070 and is spring biasedproximally by spring 1080. When the handle 1040 is in the open position,the latch 1110 is biased proximally and the detents 115 are out ofengagement with slots in the trigger insert 1090. When the movablehandle 1040 is moved through the firing stroke to its secondapproximated (closed) position, pawl 1070 is moved distally as describedabove to the disengaged position. As pawl 1070 is moved distally, latch1110 is moved distally due to the engagement of tab 1113 with pawl 1070.When the pawl 1070 is in its distal position, the detents 1115 on thelatch 1110 engage notches on the trigger insert 1090. This retains thelatch 1110 and therefore the pawl 1070 in the distal position, allowingthe handle 1040 to move back to the open position with the rack teeth1062 bypassing the pawl teeth 1072 due to the distal position of pawl1070. The override 1078 can be used to disengage the latch 1110 to resetthe rack 1060 and pawl 1070 to engagement.

It is envisioned in one embodiment that cam surface 1064 is configuredto contact pawl 1070 when movable handle 1040 is between about 0.01inches and about 0.05 inches (e.g., about 0.03 inches) from its secondapproximated position. Further, ratchet mechanism 1050 may be configuredsuch that cam surface 1064 contacts pawl 1070 after staples have beenfired from surgical stapling device 1000 or after a knife (e.g., 188, asdescribed above with respect to another embodiment) has been translatedto sever tissue, for example. In such instances, ratchet mechanism 1050would help ensure that a surgical function would be completed prior to auser moving movable handle 1040 towards its first open position.

In the illustrated embodiments, pawl 1070 also includes an override1078. Override 1078 is configured to allow a user to disengage rackteeth 1062 and pawl teeth 1072 from each other. Here, actuation ofoverride 1078 prior to movable handle 1040 reaching the predeterminedposition allows movable handle 1040 to be moved towards its first openposition, e.g., to reset ratchet mechanism 1050. To use override 1078for disengaging rack teeth 1062 and pawl teeth 1072 from one another, anoperator may translate override 1078 distally. Translation of override1078 distally moves pawl 1070 distally against the bias of spring 1080and correspondingly disengages pawl teeth 1072 from rack teeth 1062,thus allowing movable handle 1040 to move towards its first openposition prior to movable handle 1040 reaching the predeterminedposition.

It is envisioned that instrument accessories may be used to assist inperforming particular steps of the above described procedures. Forexample, an anal dilator may be inserted into the anus prior toperforming the above-described method steps to provide easier access tothe surgical site. An obturator may be used to assist in placement ofthe dilator. Also, an expandable introducer may be provided to reducethe trauma that results from insertion of the stapling device into theanus. Further, any combination of the components discussed aboveincluding the stapling device, anvil assembly, insertion handle,speculum anal dilator, and/or an obturator may be included in a kit toperform a hemorrhoidal treatment procedure.

It is noted that by providing a surgical stapler having a removableanvil assembly, visibility at the surgical site is greatly improved.This is especially important during placement of the purse string sutureand cinching of the purse string suture about the anvil center rod.

It will be understood that various modifications may be made to theembodiments disclosed herein. Therefore, the above description shouldnot be construed as limiting, but merely as exemplifications ofdisclosed embodiments. Those skilled in the art will envision othermodifications within the scope and spirit of the claims appended hereto.

The invention claimed is:
 1. A ratchet mechanism for use with a surgicalstapling device, the ratchet mechanism including: a rack having rackteeth and a cam surface, a pawl having pawl teeth, the rack teeth andthe pawl teeth being configured for engagement with each other; and aspring disposed in mechanical cooperation with one of the pawl and therack, the spring being positioned to bias at least one of the pawl andthe rack towards the other to engage the rack teeth and the pawl teeth,wherein the cam surface is configured to disengage the pawl teeth andthe rack teeth upon the cam surface contacting the pawl and wherein theratchet mechanism is configured to substantially prevent a movablehandle of the surgical stapling device from moving towards a first openposition until the movable handle reaches a predetermined position,wherein the surgical stapling device further includes an overridedisposed in mechanical cooperation with the pawl, the overrideconfigured to allow a user to disengage the pawl teeth from the rackteeth before the movable handle reaches the predetermined position,wherein disengagement of the pawl teeth from the rack teeth allows themovable handle to be moved towards its first open position.
 2. A ratchetmechanism for use with a surgical stapling device, the ratchet mechanismincluding: a rack having rack teeth and a cam surface, a pawl havingpawl teeth, the rack teeth and the pawl teeth being configured forengagement with each other; and a spring disposed in mechanicalcooperation with one of the pawl and the rack, the spring beingpositioned to bias at least one of the pawl and the rack towards theother to engage the rack teeth and the pawl teeth, wherein the camsurface is configured to disengage the pawl teeth and the rack teethupon the cam surface contacting the pawl and wherein the ratchetmechanism is configured to substantially prevent a movable handle of thesurgical stapling device from moving towards a first open position untilthe movable handle reaches a predetermined position, wherein the rack ispivotably coupled to the movable handle of the surgical stapling device.3. A ratchet mechanism for use with a surgical stapling device, theratchet mechanism including: a rack having rack teeth and a cam surface,a pawl having pawl teeth, the rack teeth and the pawl teeth beingconfigured for engagement with each other; and a spring disposed inmechanical cooperation with one of the pawl and the rack, the springbeing positioned to bias at least one of the pawl and the rack towardsthe other to engage the rack teeth and the pawl teeth, wherein the camsurface is configured to disengage the pawl teeth and the rack teethupon the cam surface contacting the pawl and wherein the ratchetmechanism is configured to substantially prevent a movable handle of thesurgical stapling device from moving towards a first open position untilthe movable handle reaches a predetermined position, wherein thepredetermined position of the movable handle is between about 0.01inches and about 0.05 inches from a second approximated position of themovable handle.